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    Petroleum, Fuel Oxygenates, and Tars

Consulting Regarding Site Closure Requests Pursuant to the California State Water Board Low-Threat Closure Policy.  Ms. Zemo is engaged by multiple clients to provide strategic and technical oversight of closure requests of petroleum releases throughout California. Sites include UST releases and non-UST releases such as ASTs, pipelines and crude oil.

California State Water Board  Low-Threat UST Case Closure Policy. Ms. Zemo provided technical expert support during development of the Policy (SWRCB Resolution 2012-0016) and associated Technical Justification Documents.

California State Water Board 2012 LUFT Manual.  Ms. Zemo was the primary author of three chapters of the Revised California LUFT Manual (Site Assessment; Fate and Transport of Petroleum in the Subsurface; and Laboratory Analysis and Methods), and provided expert review of several other chapters. The Manual was written on behalf of the UST Program of the State Water Resources Control Board (SWRCB) and was finalized in September 2012.  Ms. Zemo presented the Manual contents on behalf of the SWRCB at several conferences in 2010, 2011 and 2013.  

Identification of Hydrocarbon Type and Assistance with Regulatory Permit Negotiations.  Ms. Zemo reviewed analytical data and TPH chromatograms for hundreds of samples to distinguish between crude oil and diluent in impacted soil.  This technical distinction, along with clarification of permit requirements, resulted in regulatory approval of tens of thousands of cubic yards of crude oil-impacted soil to be beneficially re-used in an active oil field.   

Site Closure with Measurable Free Product in Place.  Ms. Zemo provided technical oversight and regulatory strategy that resulted in the closure of a UST site impacted by weathered diesel in which approximately 4 inches of apparent thickness of product was left in place.  The technical issues included: (1) assessment of product mobility/recovery, (2) proving that previous groundwater data were biased by non-dissolved product and that the dissolved-phase plume was below regulatory criteria. The project team showed that the regulatory screening levels for “TPH” in soil vapor were excessively conservative and the cumulative vapor risk was actually acceptable.  The regulatory strategy framed site conditions within the criteria outlined in the California SWRCB Resolution 2009-0081, which justified this as a low-threat site eligible for closure.

Risk-Based Investigation and Closure for Multiple Re-Development Properties.  Since forming Zemo & Associates, Ms. Zemo has been routinely engaged as a technical specialist to enhance and focus the site investigation and remediation strategy for several former petroleum bulk storage facilities, service stations, and rail yards.  She has interacted with regulators to negotiate cleanup goals for soil, groundwater and product (including minimizing the reliance on TPH); focused the investigation on constituents that would drive the risk evaluation; assisted with the risk assessment; and developed streamlined remedial strategies.  These consulting services have resulted in significant reduction of remediation costs and reduced the time to site closure and redevelopment.  Clients include large and small consulting firms, industrial companies, developers and the US Military. 
Development of Specialty Technical Field and Laboratory Protocols to Produce More Accurate Groundwater Characterization for Petroleum Sites. In the last several years, Ms. Zemo has been engaged on a number of sites to review groundwater data to assist consultants and responsible parties with accurately assessing the impact of petroleum to groundwater quality.  Based on her long history of applied research into false TPH detections and interferences from non-dissolved petroleum (see publications/presentations lists), Ms. Zemo has developed protocols focused on isolating and quantifying the dissolved petroleum hydrocarbons in water samples.  These protocols have significantly reduced reported groundwater concentrations at sites, whether they are quarterly monitoring data from wells or groundwater screening samples from initial site investigations.  In all cases the maximum reported concentrations in groundwater were reduced considerably (some up to 100%), resulting in a smaller or lower-concentration plume, thus reducing monitoring and remediation costs.
Expedited Site Characterization and Remediation of Fuel Release. Ms. Zemo directed the expedited characterization and remediation work that focused on gasoline, diesel, and jet fuel released from a pipeline. MTBE and other fuel constituents were found in groundwater 60 feet below the water table and approximately 1000 feet downgradient of the release point.  Site conditions were quickly and cost-effectively characterized in three dimensions with minimal disturbance using CPT and discrete-depth groundwater sampling (Hydropunch). A targeted monitoring and extraction well network was constructed at multiple depths. The fate and transport of BTEX and MTBE was evaluated using groundwater monitoring data and hydrogeologic modeling; these findings were used to refine regulatory requirements for remediation. A three-phase (product, vapor, groundwater) extraction and treatment system was installed to remediate elevated concentrations of BTEX and MTBE and to protect downgradient domestic wells.
Expedited Site Characterization, MTBE / TBA Release. Ms. Zemo directed the expedited groundwater characterization that focused on fuel oxygenates emanating from a newly-constructed retail service station. High concentrations of both MTBE and TBA were found in groundwater beneath the facility, with no record of liquid-phase fuel release from the USTs, piping, or dispenser sumps. A detailed soil vapor survey was performed and a tracer test was conducted on the UST system to identify the source.  A three-dimensional CPT/Hydropunch groundwater screening program delineated the lateral and vertical extent of the plume prior to installation of a monitoring well network.  A design for hydraulic control of the plume was recommended, including treatment options for the high (up to 1:1) MTBE:TBA ratio.

Remediation and Closure of Gasoline Release in Urban Neighborhood. Ms. Zemo directed this project that focused on a gasoline release from city operations in a largely residential area. Timely site closure was important to the city for property redevelopment. Her project team re-engineered the previously existing site remediation system to optimize product/vapor recovery and biodegradation of BTEX in groundwater. The team worked with the regulatory agency to proactively educate the residents about the overall approach to ultimate site closure, which would rely in part on risk assessment.  Once the active remediation system reached asymptotic recovery of product and BTEX, it was shut off and groundwater and soil vapor data were collected quarterly under natural conditions for about a year to assess the potential risk to human health posed by the residual BTEX in soil and groundwater.  Results of the risk assessment and evidence for natural attenuation of the groundwater plume were presented to the public and the agency. Site closure was acceptable to the public and approved by the agency.
Soil, Groundwater and Utility Backfill Investigation and Cleanup, Fuel Pipeline Release. Ms. Zemo directed a project that involved site investigation and remediation in response to a leak from a pipeline that conveys gasoline, diesel, and jet fuel. The leak intersected a town’s utility line network (including sewer and water lines). Work included characterizing local hydrogeology, identifying natural and man-made migration pathways, and quickly defining the extent of fuel in soil and groundwater and along the backfill of utility lines. Numerous private wells were sampled and video logged to confirm well construction information. A soil vapor/product/groundwater extraction system was installed and operated to contain and remediate MTBE and other fuel constituents in native soil, groundwater, and utility backfills. Project activities also included investigating and remediating combustible vapors in the sewer system through vapor extraction and sewer rehabilitation, and participating in community relations programs.
Development of Risk-Based “Consistent Approach” for Portfolio of Sites, Former Pipeline Route. California is known for its inconsistency in remedial requirements between regulatory agencies and between case workers within an agency. Ms. Zemo developed a strategic and technical “consistent approach” for a major oil company client by which multiple sites along a 400-mile long former pipeline in central and northern California, all affected by degraded crude oil, would be evaluated as a portfolio in a consistent, risk-based manner. Properties along the former pipeline are being developed primarily as residential subdivisions.  Details included the required analytical suite and criteria for site closure. This approach allowed for efficient and systematic site evaluation by the client and multiple agencies instead of the usual protracted individual site negotiations.  Between 1995 and 2000, multiple sites were closed by either local or state agencies using the “consistent approach”.
Risk-Based Investigation and Evaluation, Former Rail Yard. Ms. Zemo developed the strategic approach and directed regulatory interaction for a fast-track, focused, risk-based investigation and evaluation of a former rail yard near San Francisco Bay that was subsequently redeveloped for commercial use. Petroleum hydrocarbons and metals (especially lead) were present at the site as “background” within the fill and as a result of site operations.  These constituents, along with minor chlorinated VOCs, were assessed with respect to future human receptors and sensitive ecological receptors. Site closure was granted by the state agency within 12 months of implementing investigation fieldwork.
Site Characterization and Human Health Risk Assessment, Former Pipeline Route. Ms. Zemo managed this project for a major oil company client in which soil within the saturated zone along a former pipeline contained residual separate-phase crude oil. The remedial selection by the former consultant was excavation and biotreatment. Ms. Zemo negotiated with two state regulatory agencies to leave the petroleum in place based on its low water solubility and limited risk to human health under a residential exposure scenario. She demonstrated to the agency that TPH detections in groundwater samples were the artifacts of positive interferences to the TPH measurement and were not representative of dissolved-phase petroleum. The site was closed in 1995 and has been developed as a subdivision.  This was one of the first risk-based site closures issued by the California RWQCB-CV.
Technical Review Regarding Site Investigation or Remediation Focused on Tars or Creosote.  Ms. Zemo provided specialty technical review on several sites impacted by tars or creosote (MGP facilities, wood treating facilities, and a roofing tar manufacturing facility).  She focused on the fate and transport of the dense separate phase and the dissolved plume, and the interpretation of “TPH” data and PAH ratios.  On several projects, Ms. Zemo identified significant interference to groundwater analytical data by a non-dissolved component, which resulted in dramatic decreases to remediation requirements.  

Site Characterization and Reassessment of Remedial Approach, Former Gasification Plant.  Ms. Zemo managed this project for a municipal client in which site characterization by others had resulted in selection of an excavation and treatment alternative for remediation of 7000 cubic yards of soil affected by petroleum hydrocarbons. With limited additional characterization and working closely with a specialty analytical laboratory, forensic chemistry (fingerprinting) was used and a technical argument was developed about the risk to human health and groundwater quality posed by the material. Although this was very early for a “risk-based” solution in California (1991-1992), she successfully negotiated with the regulatory agency to leave the affected soil in place and received site closure after four quarters of groundwater monitoring.  The cost-effective and timely site closure was critical for the client’s property redevelopment budget and schedule.

  -Chlorinated Compounds and Other VOCs

Soil and Groundwater Remediation, Former Chemical Repackaging Facility. For an industrial client, Ms. Zemo managed a large remediation project involving significant soil and groundwater contamination by chlorinated and non-chlorinated VOCs. The presence of DNAPL, high dissolved concentrations, and a mixture of 20 different chemicals required creative selection of remedial technology. Soil remediation focused on removal of DNAPL in the unsaturated zone; techniques included soil vapor extraction and treatment using a resin-absorption unit or a catalytic oxidizer. Groundwater containment was achieved by extraction followed with treatment through two air strippers in series and off-gas treatment using catalytic oxidation. Reduction of concentrations within the plume was accomplished with an in-situ enhanced anaerobic biodegradation program. The site remedial strategy was carefully developed with state regulators within the context of significant off-site (upgradient and transgradient) sources of similar VOCs.
Groundwater Assessment and Remediation, Former Metals Recycling Facility. Ms. Zemo managed this large, multidisciplinary project for an industrial client in which chlorinated VOCs had impacted groundwater within multiple flow zones to a depth of 80 feet and extended about 0.5-mile downgradient. The impacted area included a neighborhood with many wells used for irrigation. To reduce investigation impact and the client's overall costs, Ms. Zemo successfully educated and convinced the regulators that groundwater screening results were representative; this was one of the first large-scale screening programs in Northern California (1990-1991). An innovative, multiple-zone, discrete-depth groundwater survey using CPT and BAT/Hydropunch sampling methods was used to delineate the lateral and vertical extent of groundwater contamination. A targeted, cost-effective monitoring well network was installed. Ms. Zemo designed and implemented the installation, aquifer testing, and hydrogeologic evaluation of an on-site and off-site extraction well network for hydraulic containment. She evaluated off-site sources of VOCs and provided extensive interaction with regulatory agencies on behalf of the client and its legal counsel.
Soil and Groundwater Assessment and Remediation, Former Paint Thinner Facility. Ms. Zemo managed this project for a private client in which ketones and other non-chlorinated VOCs had leaked from an underground storage tank and affected soil and groundwater. Site characterization included reassessment of the previous consultant's interpretation of site groundwater contamination, resulting in a significant decrease in project scope and cleanup costs. Site remediation included an in-situ enhanced biodegradation pilot study and the excavation and aeration of approximately 3700 cubic yards of VOC-affected soil.
Hydrogeological Assessment, Electronics Manufacturing Facility. Ms. Zemo managed this project in which groundwater was affected by chlorinated VOCs emanating from a former underground storage tank. Site characterization included a discrete-depth groundwater survey using CPT and BAT/Hydropunch sampling methods to delineate the lateral and vertical extent of affected groundwater and to assess the influence of site stratigraphy on direction of groundwater flow and distribution of chemical concentrations. She negotiated successfully with the regulatory agency to modify the previous monitoring program, giving the client a cost savings of 70 percent.  After aggressive source removal in shallower groundwater zones, Ms. Zemo also successfully negotiated a natural attenuation remedial solution for deeper zones.  

CERCLA Site Assessments. Ms. Zemo conducted numerous investigations at pre-remedial CERCLA/SARA hazardous waste sites (such as dry cleaners, metal plating facilities, machine shops, and hazardous waste disposal facilities) as a contractor for USEPA Region 9. She evaluated site operations, waste streams, and waste disposal practices using historical records. She assessed stratigraphy, hydrogeology, and soil and groundwater quality using soil borings and monitoring wells. Assessment results determined site eligibility for the National Priorities List.